linux-kernel - Re: [PATCH v2 11/16] x86/compressed: move startup32_load

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 18 Nov 2022 17:44:20 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Ard Biesheuvel <ardb@...nel.org>
Cc:     linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Michael Roth <michael.roth@....com>
Subject: Re: [PATCH v2 11/16] x86/compressed: move startup32_load_idt() into
 .text section

On Wed, Sep 21, 2022 at 04:54:17PM +0200, Ard Biesheuvel wrote:
> Convert startup32_load_idt() into an ordinary function and move it into
> the .text section. This involves turning the rva() immediates into ones
> derived from a local label, and preserving/restoring the %ebp and %ebx
> as per the calling convention.
> 
> Also move the #ifdef to the only existing call site. This makes it clear
> that the function call does nothing if support for memory encryption is
> not compiled in.

I'm not crazy about all that ifdeffery in there but this will need a
serious look.

Btw, you can drop one, diff ontop:

---
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index bc5bd639217e..a862fd8ac0bd 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -726,9 +726,7 @@ SYM_DATA_START(boot32_idt)
 	.quad 0
 	.endr
 SYM_DATA_END_LABEL(boot32_idt, SYM_L_GLOBAL, boot32_idt_end)
-#endif
 
-#ifdef CONFIG_AMD_MEM_ENCRYPT
 	.text
 	.code32
 /*

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette